I know this might not help, this is just my 2 cents ... and maybe someone
from Microsoft picks up on it;

In our company we have quite a few people using USB Flash drives (pen drives
and even iPods), mainly so they can take along the files they work on and
recently because they want to be able to check their email in different
locations (home, other offices, etc) without having to drag a laptop with or
completely (re)configure the host workstation(s) - that last option is hard
in any Internet cafe.

Currently Microsoft Outlook 2003 is the default email application in our
company, but (as most of us already know) Outlook cannot be installed on a
USB/Flash drive as a standalone application.

Thunderbird on the other hand can be installed on such a drive and be taken
along. Plug the USB drive in any Windows based computer and you're good to go!
Sure Outlook 2003 has more to offer, but the convenience factor makes more
and more people in our company switch to Thunderbird ...

Note: Most of them use Calendar (Sunbird) as an extension to deal with the
lacking calendar in Thunderbird. Far from ideal, but maybe this is where a
standalone Outlook 2003, that can run from a flash drive without having to
install Office on that workstation, could help us all and make sure that
Outlook 2003 maintains it's position as one of the best email applications ...